A conventional decorative bulb as shown in FIG. 1 comprises: a bulb L inserted in a base B which is then jacketed into a socket S, in which two leads L1 of the bulb filament are respectively connected to two power wires W by a pair of conducting plates C. However, it still reveals following drawbacks or matters to be improved:
1. The bulb L must be first inserted in a base B and then mounted into the socket S to increase production cost.
2. A conducting plate C is formed a single needle portion C1 for sticking a conducting wire W, thereby possibly influencing its electric conductance.
3. A plug P is provided on the socket bottom, but without forming well engagement between the socket and the plug, so that its water proof effect is quite limited.
4. The cylindrical surface of bulb L is smoothly jacketed into the base to thereby be easily withdrawn.
The present inventor has found these phenomena and invented the present bulb with annular groove and water-proof socket.